[smspence]

I am using Firefox 15 on Windows XP. I had no problems whatsoever.

I opened up windows task manager, and watched the mem usage for firefox.exe. Before navigating to that webpage, it was using 150 MB of memory. I went to the webpage and scrolled down as expected, and saw the mem usage peak at around 430 MB when the page first loaded, then as I scrolled down and sat at the bottom of the page, it stabilized at around 300 MB.

After closing the tab and going back to leave this comment, firefox is back to about 150 MB of mem usage. I think there is a problem with your particular installation (or add-ons or drivers), not a general problem with Firefox itself.